The present invention generally relates to thermoelectric devices, and particularly to a thermoelectric device for use in a solid state thermoelectric heat pump.
The thermoelectric effect is a phenomenon that occurs when a difference in temperature exists in an electric circuit. An example of thermoelectric effect is given by the Peltier effect. In simple terms, if an electric current is passed through a metal-metal or metal-semiconductor junction, heat is liberated or absorbed at the junction depending on the direction of the electric current. The Peltier effect is reversible, i.e. if the direction of the electric current is reversed, the cold junction becomes hot and the hot junction becomes cold. It has been found that greater temperature differences are achievable by using metal-semiconductor junctions rather than metal-metal junctions. The Peltier effect is the principle of operation of solid state thermoelectric heat pumps.
In the following, the term xe2x80x9cthermoelectric devicexe2x80x9d designates a solid state device that makes use of the Peltier effect for heating or cooling a material substance. The term xe2x80x9cthermoelectric elementxe2x80x9d designates a metallic conductor or a semiconductor material bar. The term xe2x80x9cthermoelectric couplexe2x80x9d designates a combination of two thermoelectric elements that are electrically connected in series at one end thereof through an electrode.
Solid state thermoelectric heat pumps are commercially available since 1960. Initially, the heat pumps included metallic conductor thermoelectric elements. At present time, the modern technology in the field of semiconductors provides solid state thermoelectric heat pumps with thermoelectric elements formed from alloys of Bi2Te3, PbTe, SiGe, BiSb N-type and P-type doped. The thermoelectric devices that are generally known in the art have a planar configuration showing varying geometrical forms. In this kind of thermoelectric devices the thermoelectric couples are supported in a sandwich structure by means of elements made of an Al2O3 based ceramic material which is laminated together with copper.
The present invention provides a thermoelectric device with a novel arrangement of thermoelectric couples formed of metallic conductor and/or N-type and P-type semiconductor thermoelectric elements. The present invention also provides a heat pump comprising the thermoelectric device of the invention.
According to a first embodiment of the present invention, the solid state thermoelectric device includes at least an array of metallic conductor and/or N-type and P-type semiconductor thermoelectric elements assembled on a printed circuit, whereby said thermoelectric elements form thermoelectric couples electrically connected in series, and is characterised in that it has a structure formed of:
at least a pair of laminated elements, each formed of a supporting layer made of polymeric material and at least a layer of conductive material,
a layer of joining material interposed between said two laminated elements of polymeric material for firmly connecting them one to the other and in that,
the printed circuit is made from the layer of conductive material of the laminated elements and electrically connects in series the thermoelectric elements to form thermoelectric couples having the hot or cold sides, respectively, on only one side of the structure, and
said structure of the thermoelectric device has a spirally or circularly wound configuration.
According to a second embodiment of the present invention, the solid state thermoelectric device includes at least an array of metallic conductor and/or N-type and P-type semiconductor thermoelectric elements assembled on a printed circuit, whereby said thermoelectric elements form thermoelectric couples electrically connected in series, and is characterised in that it has a structure formed of:
a laminated element formed of a supporting layer made of polymeric material and on each face thereof a layer of conductive material,
a layer of joining material interposed between the end portions of the laminated elements in order to firmly connect them one to the other, and in that
the printed circuit is made from at least one of the layers of conductive material of the laminated element and electrically connects in series the thermoelectric elements to form thermoelectric couples having the hot or cold sides, respectively, on only one side of the structure, and
said structure has a spirally or circularly wound configuration.